In large-scale multilevel manufacturing systems, such as those encountered when manufacturing computing equipment, complex distributed supply and manufacturing networks must be monitored to ensure the quality and reliability of the products stay above specifications. In other words, component suppliers, subsystem manufacturers as well as original equipment manufacturer (OEM) system integrators and other participants, must work together through worldwide distribution channels and global manufacturing networks to ensure quality products are delivered. In such scenarios, the OEM must take the initiative to ensure that all of the sub-tier parties are working together.
Coordinating and analyzing supplier and manufacturing quality and reliability is critical to optimizing the supplier quality system and the material flows for quality assurance. However, such coordination is often complex, time consuming and very costly. For example, collecting supplier parametric data and applying statistical process control (SPC) over the entire supply chain is usually cost prohibitive for many OEMs. Additionally, in the case of a quality problem, it may take extraordinary effort, time and expense to determine which provider, within the supply chain is responsible for the failure of a given component or the sub-system. Other problems may arise by not obtaining reliable information from all party participants. In this case, the OEM may have to expend tremendous effort to ensure that the data reported is reliable and can be trusted.
In computer manufacturing, component suppliers will manufacture components, i.e., memory chips, passive devices and printed circuit boards (PCBs), etc., to be integrated into a memory module by the subsystem manufacturer (card assembler). Prior to shipment to the card assembler, these components should be tested at their fabrication facilities, with test yield reported to the OEM. Once the components have passed such testing, they are then shipped to the card assembler, at which time the components are assembled together, tested and results reported to the OEM, and then shipped to the system integrator. The system integrator or OEM, will then manufacturer the final product for the consumer.
In this example, during in process testing at the system integrator, the system integrator may have detected that one of the subsystem components, e.g., memory card, is not properly functioning (failed). It is now incumbent upon the system integrator, to determine whether the failure of the component occurred during the final assembly process, the subassembly process or at the component manufacturer, itself. In making such a determination, it is important to ascertain whether (i) there have been reliable testing programs and (ii) the upstream vendors, component suppliers, etc. are reliably reporting failures accurately. All of these determinations require resources to undertake.
In this type of multilevel manufacturing environment, the process of determining the failure root cause and the party that is responsible for quality problems can be quite a daunting task. In one solution to such problem, the OEM would need to supervise multiple layers within the supply chain, which may include a large number of facilities. This may be cost prohibitive for many manufacturers and in the least would be very cumbersome to all involved parties. Due to perceived liabilities, it is conceivable that the upstream vendors would find such supervision intrusive and unwarranted thus denying access to their facilities.
To apply SPC over a complex multi layer system is usually cost prohibitive for the following reasons:
the effort spent in data collection;
the engineering know-how to identify critical parameters; and
the workforce needed to analyze the accumulated data.